Film-forming apparatus component and method for cleaning same

ABSTRACT

There are provided a film forming equipment component having a structure in which an deposited film d formed on the component can be separated from the component for a time period shorter than the prior art to reduce damage due to a cleaning fluid S, and a method of cleaning such a component. A metal film layer  2  electrochemically less noble than the matrix metal material  1  of the aforementioned component is formed on the surface of the matrix metal material  1  through thermal spraying, vapor depositing, sputtering, laminating or other process. Alternatively, a second metal film layer  3  electrochemically more noble than the aforementioned matrix metal material  1  is formed on the surface of the metal film layer  2  through said thermal spraying or other process. Thus, a local cell is formed between the metal film layer  2  and the matrix metal material  1  or the second metal film layer  3 . Therefore, the deposited film d can be separated from the matrix metal material  1  for an extremely shortened time period, without damaging the matrix metal material  1  itself from the cleaning fluid S.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a component for a film formingequipment which uses a film forming material to form various thin-films,and a method of cleaning such a component.

BACKGROUND ART

In a manufacturing process of semiconductor components used in largescale integrated circuits (LSI), solar batteries, liquid crystaldisplays, plasma displays and the like, the film-forming equipments forforming thin films on substrates through vapor depositing, sputtering,CVD or other process with a film-forming materials has been used.

The aforementioned film-forming material has also formed a depositedfilm over the surfaces of the components such as a buffer platesrepresented by a substrate mask and a wafer support frame in the filmforming equipments when a thin film has been formed therein.

The aforementioned deposited film thickly accumulates on the componentsas a number of substrates are successively processed to form filmsthereon in the film forming equipments. If the accumulated depositedfilm is broken at a certain time point, dust occurs. The dust may fallon a substrate on which a film is being formed, resulting in damage ofthe intended properties in the formed film. This reduces the yield inthe manufacturing products.

To overcome such a problem, Japanese Laid-Open Patent Application No.1991-87357 has proposed a structure in which a deposited film thicklyaccumulated on a component cannot easily be broken/separated from thesurface of the component as a result of a mechanical process such ascutting or peeling or a blasting process to the surface of thecomponent.

If the aforementioned processed component is used in the film formingequipments, it is preferable in that the deposited film cannot easily bebroken/separated from the surface of the component when a thin film isbeing formed.

Where the component from which the deposited film has been removed is tobe re-used, however, it is difficult to remove the deposited filmthrough the mechanical removing process because the above structure isconfigured to prevent the deposited film being easily broken/separatedin the first place.

A chemical removal process for dissolving an deposited film by use of acleaning fluid has also been proposed. Such a chemical process requiresthat a component with a deposited film is dipped in the cleaning fluidfor about two days. This is disadvantageous in that the component may bemore dissolved than the deposited film depending on the types of thecleaning fluid and deposited film.

To overcome such a problem, Japanese Laid-Open Patent Application No.1999-124661 has proposed a component in which, to remove the depositedfilm while suppressing the dissolution of the component itself, thesurface of a matrix metal material (e.g., aluminum or its alloy) in theaforementioned component is covered with a lower readily-soluble metallayer consisted of a metal more easily soluble in acid cleaning fluidthan the matrix metal material (e.g., copper or its alloy), a porousmetal film being then formed over the lower readily-soluble metal layer(e.g., see Patent document 2).

When the cleaning fluid reaches the lower readily-soluble metal filmlayer from the edges of the component and surface defects of a depositedfilm, it dissolves this lower readily-soluble metal film layer at thefirst time.

Therefore, the deposited film can be separated from the component for ashorter time period. In the aforementioned component according to theprior art, however, time period required to separate the deposited filmfrom the component after the cleaning fluid has reached the lowerreadily-soluble metal film layer via the aforementioned porous metalfilm to dissolve the lower readily-soluble metal film layer is between 5and 15 hours. Thus, time period for which the component is dipped in thecleaning fluid can certainly be shortened. However, the component mustyet be dipped in the cleaning fluid for a long time, resulting in not alittle damage to the matrix metal material.

Furthermore, the damage to the matrix metal material also results fromthe selection of material for the aforementioned lower readily-solublemetal film layer.

In other words, the prior art selected a metal more easily soluble intothe acid cleaning fluid than the matrix metal material as the materialfor the aforementioned lower readily-soluble metal film layer. If thematrix metal material is aluminum or its alloy and when the component isdipped in the cleaning fluid for a long time, however, a local cell willbe formed between the matrix metal material of aluminum or its alloy andthe lower readily-soluble metal film layer of copper or its alloy by thepotential difference since the aluminum is less noble than the copper orits alloy as can be seen from the natural electrode potential. This maymore dissolve the matrix metal material.

An object of the present invention is thus to provide a component for afilm forming equipment having a structure which can separate a depositedfilm from the component for a time period shorter than that of the priorart and reduce the damage to the matrix metal material from the cleaningfluid, and a method of cleaning such a component.

DISCLOSURE OF THE INVENTION

To overcome the aforementioned problems of the prior art, the componentaccording to the present invention which is to be used in a film formingequipment for forming a thin film is characterized by that it comprisesthe surface of a matrix metal material formed with a metal film layerelectrochemically less noble than the matrix metal material through aspraying, vapor depositing, sputtering, laminating or other process.

In such an arrangement, if the processed component is dipped in acleaning fluid, a local cell is formed between the matrix metal materialand the aforementioned metal film layer by a natural electrode potentialdifference therebetween, with the local current then flowing from thematrix metal material to the metal film layer.

On the other hand, the metal film layer preferentially dissolves andremains in the cleaning fluid as metal ions.

In general, when a local cell is formed between two different metals,one of these metals less noble than the other and having its largernatural electrode potential difference will more rapidly be dissolved.

Therefore, the materials for the aforementioned metal film layer maysuitably be selected in consideration with the type of matrix metalmaterial and the potential difference between the matrix metal materialand the deposited film.

By forming a second metal film layer electrochemically more noble thanthe aforementioned matrix metal material on the surface of theaforementioned metal film layer through a thermal spraying, vapordepositing, sputtering, laminating or other process, a local cell isalso formed between the second metal film layer and the lower metal filmlayer. Thus, the dissolution advances from both the interfaces betweenthe lower metal film layer and the matrix metal material and between thelower metal film layer and the second metal film layer.

At this time, the potential difference between the second metal filmlayer and the lower metal film layer becomes larger than the potentialdifference between the matrix metal material and the lower metal filmlayer. Thus, the dissolution will more intensely advance in the vicinityof the interface between the second metal film layer and the lower metalfilm layer.

Now, if the potential in the deposited film is higher than that of thematrix metal material (for example, if the deposited film is made ofmolybdenum and the matrix metal material is aluminum or its alloy) andif the potential of the second metal film layer is higher than that ofthe matrix metal material, the matrix metal material becomes less noblethan those of the deposited film and second metal film layer, resultingin the potential of the matrix metal material being lower than that ofthe deposited film or second metal film layer. This may cause the matrixmetal material to be dissolved by the cleaning fluid.

In such a case, thus, the dissolution may be avoided by applying apositive electric field to the matrix metal material and immobilizingthe matrix metal material so that it behaves as a metal more noble thanthe deposited film or second metal film layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a), (b) and (c) are cross-sectional views, partially enlarged,of a component according to the present invention: FIG. 1(a) shows thecomponent when it is dipped in a cleaning fluid after a metal film layerhas been formed on the surface of a matrix metal material; FIG. 1(b)shows the component when it is dipped in the cleaning fluid after thesecond metal film layer has been formed on the surface of the metal filmlayer; and FIG. 1(c) shows a cleaning process for removing the depositedfilm by applying a positive electric field to the matrix metal material.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1(a) is an enlarged cross-sectional view of a component for a filmforming equipment in which a metal film layer 2 is formed on the surfaceof a matrix metal material 1. The component comprising the matrix metalmaterial 1 may include buffer plates such as substrate masks in the filmforming equipment or wafer support frame. When a thin film is formed ona substrate from a film forming material in the film forming equipment,a deposited film d also deposits on the aforementioned component inaddition to the substrate.

This deposited film thickly accumulates on the component as a number ofsubstrates are successively processed to form films thereon in the filmforming equipment. If the accumulated deposited film is broken at acertain time point, dust occurs. The dusts may fall on the substratebeing processed to damage the intended properties of the formed film.

To remove this adhesion film d, the matrix metal material 1 may bedipped in a cleaning fluid S. However, the matrix metal material 1 mustbe dipped in the cleaning fluid S for a considerable time period (e.g.,about two days) until the cleaning fluid S sufficiently penetrates intothe deposited film d to separate it from the matrix metal material 1.This may also damage the matrix metal material.

Furthermore, the time period for which the matrix metal material 1 mustbe dipped in the cleaning fluid S may be shortened by forming a lowerreadily-soluble metal film layer on the surface of the matrix metalmaterial 1 and further forming a porous metals film on the surface ofthis lower readily-soluble metal film layer. Even in such a case, timerequired to separate the deposited film from the matrix metal material 1is in a range between 5 hours and 15 hours. This means that thecomponent must be yet dipped in the cleaning fluid S for a long time,resulting in not a little damage to the matrix metal material 1.

A preferred material for forming the aforementioned lowerreadily-soluble metal film layer is a metal more readily soluble to thecleaning fluid S than the matrix metal material 1, for example, a copperalloy. If the matrix metal material 1 is or an aluminum alloy, thenatural potential electrode measurement data show that copper alloy (JISA5052 is −1.02 in one mol/l of sulfuric acid liquid) is more noble thanor an alloy of aluminum (JIS A5052 is −1.70 in one mol/l of sulfuricacid liquid), as shown in Table 1. If the matrix metal material 1 of oran alloy of aluminum is dipped in the cleaning fluid for a long time,therefore, a local cell may be formed between or an alloy of aluminumand or an alloy of copper from the potential difference therebetween topromote the oxidization so that the matrix metal material 1 will more bedissolved.

It is intended herein that a more noble metal is one located above thereference metal in the table 1 while a less noble metal is one locatedbelow the reference metal in the table 1. Thus, whether a metal is moreor less noble is determined relative to the reference metal.

The present invention can separate the deposited film d from the matrixmetal material 1 along with the metal film layer 2 for a shortened timeperiod (e.g., about 45 minutes) by forming a metal film layer 2containing a metal less noble than the matrix metal material 1 on thesurface of the matrix metal material 1 through thermal spraying, vapordepositing, sputtering, laminate or other process and by causing a localcell to be formed between the matrix metal material 1 and the metal filmlayer 2 to promote the dissolution of the metal film layer 2 when thematrix metal material 1 is dipped in the cleaning fluid S.

In other words, the local cell is formed between the matrix metalmaterial 1 and metal film layer 2 by the potential differencetherebetween, the local current then flowing from the matrix metalmaterial 1 to the metal film layer 2.

On the other hand, the metal film layer preferentially dissolves andremains in the cleaning fluid as metal ions.

For example, if the metal film layer 2 is Al −5% In (its naturalpotential is −1.17 in one mol/l of sulfuric acid liquid) and the matrixmetal material 1 is Al alloy (the natural electrode potential of JISA5052 is −0.70 in one mol/l of sulfuric acid liquid) and when thedeposited film d of 99.99% Al (4N—Al) (its natural potential is −0.86 inone mol/l of sulfuric acid liquid) deposits over the metal film layer 2,a local cell is formed between the matrix metal material 1 and the metalfilm layer 2 in the sulfuric acid liquid. The metal film layer 2 isionized and dissolved into the sulfuric acid liquid.

The metal film layer 2 may suitably be selected from a group consistingof metals and alloys that can easily form the local cell between themetal film layer 2 and the matrix metal material 1, based on the naturalpotential E (Vvs.SCE) in the cleaning fluid S.

Referring now to FIG. 1(b), there is shown a second metal film layer 3formed on the surface of the aforementioned metal film layer 2 throughthermal spraying, vapor depositing, sputtering, laminating or otherprocess, the second metal film layer 3 containing a metal more noblethan the matrix metal material 1.

In this case, since, in the cleaning fluid S, a local cell is formedbetween the metal film layer 2 and the matrix metal material 1 andanother local cell is also formed between the metal film layer 2 and thesecond metal film layer 3, the dissolution advances from both theinterfaces between the metal film layer 2 and the matrix metal material1 and between the metal film layer 2 and the second metal film layer 3,the deposited film d can be separated from the matrix metal material 1more rapidly than the case of FIG. 1(a) that only the metal film layer 2is formed.

For example, if the metal film layer 2 is Al-5% In; the second metalfilm layer 3 is Al alloy (the natural potential of JIS A2017 is −0.56 inone mol/l of sulfuric acid liquid); and the matrix metal material 1 isAl alloy (JIS A5052) and when 99.99% Al (4N—Al) film deposits on thesecond metal film layer 3, local cells are formed between the matrixmetal material 1 and the metal film layer 2 and between the second metalfilm layer 3 and the metal film layer 2, respectively, in the sulfuricacid liquid. Thus, the metal film layer 2 is ionized and dissolved intothe sulfuric acid liquid.

At this time, time required to dissolve the metal film layer 2 andseparate the deposited film d from the matrix metal material 1 was about15 minutes.

Referring now to FIG. 1(c), reference numeral 4 denotes a power sourcefor applying a positive electric field to the matrix metal material 1 sothat it will function as anode. The negative side of the power source 4is connected to a cathode 5.

If the deposited film d has its potential higher than that of the matrixmetal material 1 or if the second metal film layer 3 has its potentialhigher than that of the matrix metal material 1, the matrix metalmaterial 1 may be less noble than the deposited film d or the secondmetal film layer 3. In this case, the matrix metal material 1 maydissolve into the cleaning fluid S.

However, this can be avoided by applying a positive electric field fromthe power source 4 to the matrix metal material 1 so that the matrixmetal material 1 will be immobilized to behave as a metal more noblethan the deposited film d or the second metal film layer 3.

As will be apparent from the above description, the present inventioncan separate the deposited film d from the matrix metal material 1 foran extremely shortened time period, without damaging the matrix metalmaterial 1 itself from the cleaning fluid S by providing theaforementioned metal film layer 2 on the surface of the matrix metalmaterial 1 of the component to form the local cell between the metalfilm layer 2 and the matrix metal material 1 or by providing the secondmetal film layer 3 on the surface of metal film layer 2 to form thelocal cell between the metal film layer 2 and the second metal filmlayer 3. Thus, it can be promoted to reuse the component while the lifethereof can be extended.

INDUSTRIAL APPLICABILITY

As described, the present invention provides the component for the filmforming equipments and the method of cleaning the same are suitable foruse in formation of the thin film on the substrate such as buffer plate(e.g., substrate mask) or wafer support plate from the film formingmaterial through vapor depositing, sputtering, CVD or other processsince the deposited film can be separated from the film formingequipment component for a shortened time period so that the matrix metalmaterial can be less damaged by the cleaning fluid and since thecomponents of the present invention and method thereof are led to extendthe life of the components, reduce the running cost for the film formingequipment, and save the resource.

1. A component for a film forming equipment forming a thin film on asubstrate, the component being characterized by that a metal film layerelectrochemically less noble than the matrix metal material of saidcomponent is formed on the surface of the matrix metal material throughthermal spraying, vapor depositing, sputtering, laminating or otherprocess.
 2. The component as claimed in claim 1, characterized by that asecond metal film layer electrochemically more noble than said matrixmetal material is formed on the surface of said metal film layer throughthermal spraying, vapor depositing, sputtering, laminating or otherprocess.
 3. A method of cleaning a component for a film formingequipment, characterized by that after a thin film has been formed onthe substrate by the film forming equipment, the component as claimed inclaim 1 or 2 is dipped in a cleaning fluid to remove an deposited filmconsisting of the film forming material from the component.
 4. Themethod as claimed in claim 3, characterized by that a positive electricfield is applied to the matrix metal material of said component dippedin the cleaning fluid.